1. Field of the Invention
The present invention relates to a system for separating material from an aqueous medium by filtration.
2. Description of the Prior Art
In many industrially important processes it is necessary to separate material from a body of water, at the site at which the material is found within the body of water. Examples of such processes include skimming oil floating in the water due to oil spills, other types of pollution control, harvesting kelp, and harvesting algae. In these types of processes, a filter system installed in a surface vessel such as a barge or a ship is often used. Examples of such vessels have been proposed in the prior art, however none of the prior art vessels achieve the relatively high rate of filtration made possible by the unique structural design of the present invention.
U.S. Pat. No. 3,630,376, issued on Dec. 28, 1971 to Larry D. Price, shows a skimmer boat for removing oil from the surface of a body of water. The boat of Price does not have the side discharge ducts or the water diverter of the present invention.
U.S. Pat. No. 3,951,805, issued on Apr. 20, 1976 to Joseph C. Dodd, shows an algae harvesting system wherein a rotating drum is used to separate the algae from water flowing through the drum. In the Dodd device water passing through the drum is discharged from a drain pipe communicating with the interior of the drum. The drum is basically in the form of a right circular cylinder of high aspect ratio (i.e. high length to diameter ratio). Therefore, the surface area of the drum exposed to incoming water is far greater than the cross sectional area of even the largest possible drain pipe. Large pressure drops would be required to move water through the drain pipe at the same rate as the water enters the drum, when the drum is moved through the water at high speed. Such pressure drops are generally not achievable even with the aid of a mechanical pump since the pump would cavitate before the desired flow rate can be achieved, and in any event such a pump would consume energy thus increasing the cost of the operation.
The ultimate consequence of the geometric limitations of the Dodd device is that if the drum is moved through the water at high speeds, water would pile up ahead of the drum resulting in a wake which would push the product out of the way of the drum. Thus, instead of increasing product output, moving the drum through the water at higher speeds reduces the efficiency with which the product is separated from the water by the drum system of Dodd. Therefore, systems such as that of Dodd must be operated at low speeds resulting in low production rates. It should also be noted that Dodd does not show the side discharge ducts or the water diverter of the present invention.
U.S. Pat. No. 4,105,554, issued on Aug. 8, 1978 to John J. Janson, shows a split hull boat with a belt conveyor supported in its intake area. The belt conveyor of Janson is not a separator screen but is designed to conduct both water and product to holding tanks for further processing. In addition, Janson does not show the side discharge ducts or the water diverter of the present invention.
U.S. Pat. No. 4,921,605, issued on May 1, 1990 to Lucien Chastan-Bagnis et al., shows a boat for removing pollution from bodies of water. The boat has a central flow channel through which the polluted water flows. A portion of the polluted water is diverted to a decanting chamber where the buoyant pollutant is separated by a floatation type process. The water is then returned to the flow channel and discharged through the rear of the boat. In the Chastan-Bagnis et al. boat, a substantial portion of the water flowing through the boat is not filtered. Further, Chastan-Bagnis et al. do not show the side discharge ducts or the water diverter of the present invention.
U.S. Pat. No. 5,028,325, issued on Jul. 2, 1991 to William R. Hamilton, shows a pontoon boat with a continuous wire conveyer positioned between the pontoons. The conveyer picks up debris floating on the water surface and deposits them in a receptacle. Hamilton does not show the side discharge ducts or the water diverter of the present invention.
U.S. Pat. No. 5,043,065, issued on Aug. 27, 1991 to Carl F. Propp, shows a variable draft skimming vessel. Propp does not show the continuous strip filter screen, the side discharge ducts, or the water diverter of the present invention.
U.S. Pat. No. 5,149,443, issued on Sep. 22, 1992 to O'Neal Varnam, shows an oil skimmer which removes the oil contaminated water layer adjacent to the water surface. The oil contaminated water is conducted to a cascading series of tanks in which the oil is separated from the water by floatation. Varnam does not show the side discharge ducts or the water diverter of the present invention.
United Kingdom Patent Document Number 1,296,783, dated Nov. 15, 1972, by John Vernon Buckland, shows an endless conveyer mounted to a ship and used for removing pollutants from a body of water. Buckland does not show the side discharge ducts or the water diverter of the present invention.
French Patent Document Number 2,346,501, dated Oct. 28,1977, by Hideo Goto et al., shows a ship for removing floating oil from a body of water. Goto et al. do not show the side discharge ducts or the water diverter of the present invention.
Published International Patent Application Number WO 80/01293, published Jun. 26, 1980, by Peter Brian Smith, shows a ship mounted conveyer for removing floating oil from a body of water. Smith does not show the side discharge ducts or the water diverter of the present invention.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.